Use cli.toml for default start listen address

[0monish]

Description of Changes

This change addresses reviewer feedback on #4576.

As requested by @cloutiertyler, here are the changes:

• moved the persistent default listen address for spacetime start from project spacetime.json to CLI cli.toml
• threaded the already-loaded CLI Config into spacetime start instead of introducing a separate project-config lookup in that subcommand
• preserved precedence so explicit --listen-addr / -l still wins over config, and config still wins over the built-in standalone default
• documented the setting in the spacetime start CLI reference instead of the standalone runtime-config page

Behavior precedence is now:

1. Explicit CLI flag, such as spacetime start --listen-addr 127.0.0.1:5000
2. listen_addr from cli.toml
3. Built-in standalone default 0.0.0.0:3000

Example:

listen_addr = "0.0.0.0:4000"

With that config in place, spacetime start will bind to 0.0.0.0:4000 unless the user passes --listen-addr explicitly.

Implementation details:

• added a top-level listen_addr field to the existing CLI config parser and persistence path
• updated spacetime start to use the loaded CLI config rather than reading project config directly
• added/kept focused tests for --listen-addr and -l detection so config is only injected when the user did not provide an explicit listen address
• updated the checked-in CLI reference text for spacetime start

Related:

• Follow-up to Support persistent default listen-addr for spacetime start #4576

API and ABI breaking changes

None.

This change does not modify any public API or ABI. It only changes where the CLI reads an optional default value for an existing spacetime start flag.

Expected complexity level and risk

Complexity: 2/5

This is a small, localized CLI behavior change.

The main interaction point is precedence between forwarded CLI args and persisted CLI config. Risk is low because this change:

• preserves the existing standalone default when listen_addr is absent
• preserves explicit CLI --listen-addr and -l precedence
• reuses the existing cli.toml loading path instead of adding another config system

Testing

Completed:

• cargo fmt --all --check
• cargo check -p spacetimedb-cli
• cargo clippy -p spacetimedb-cli --all-targets
• cargo test -p spacetimedb-cli config::tests --lib
• cargo test -p spacetimedb-cli subcommands::start::tests --lib

Reviewer checks:

• Run spacetime start without listen_addr in cli.toml and confirm it still binds to 0.0.0.0:3000
• Add listen_addr = "0.0.0.0:4000" to cli.toml, run spacetime start, and confirm it binds to 0.0.0.0:4000
• Run spacetime start --listen-addr 127.0.0.1:5000 with config present and confirm the CLI flag still wins

[bfops]

can you explain this block? at first glance it seems like if s.starts_with("-l") passes, these other checks would as well.

[bfops]

this function can be removed entirely. if --listen-addr is passed multiple times to spacetimedb-standalone, the last one will be respected.

I would add a comment to this effect when passing --listen-addr.